Study brings insights to mechanisms of new species formation

Source: Xinhua| 2018-12-28 06:34:07|Editor: Chengcheng

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CHICAGO, Dec. 27 (Xinhua) -- A University of Michigan (UM) study of interbreeding between two species of howler monkeys in Mexico is yielding insights into the forces that drive the evolution of new species.

In the study, the researchers use the primate hybrid zone to identify parts of the genome that are likely to contain genes underlying speciation and to test for signals of the selection forces that shaped them.

At the howler monkey hybrid zone in Mexico where UM researchers have worked for about two decades, analysis of DNA samples has confirmed that black and mantled howler monkeys interbreed and produce hybrid offspring.

To test for the presence of reinforcement, a process where natural selection strengthens reproductive isolation by increasing genetic differences, UM researchers compared the DNA of black and mantled howler monkeys living the Tabasco hybrid zone to the DNA of black and mantled howler monkeys living far from the hybrid zone.

They found that the genetic differences between the two species in the hybrid zone were greater than the genetic differences between monkeys of these two species living on either side of the hybrid zone.

"We observed patterns in the genetic data suggesting that hybridization is playing a direct role in completing the speciation process by enhancing genetic differences between species," said UM doctoral candidate Marcella Baiz, the study's first author.

"We found a signal for multiple forms of natural selection driving species differences, including reinforcement," Baiz said. "This result is particularly notable because empirical evidence for reinforcement is extremely rare, especially genetic evidence."

"Speciation is a complex process that can be driven by direct and indirect mechanisms that interact to maintain and strengthen the process, and this study is one of the few natural examples that document this," Baiz added.

The study was published on Dec. 22 online in the journal Molecular Ecology.